1. Field of the Invention
This invention relates to kitchen sink drain valves, more particularly to a disc type kitchen sink drain valve mounted on a strainer that is placed in the well provided in the bottom of a kitchen sink, to open and close the drain port provided at the bottom of the well of the kitchen sink.
2. Brief Description of Prior Art
Kitchen sinks are usually provided with a well for collecting the waste water in the sink to be drained through a drain port provided therein. The drain port is usually provided with a drain valve which is mounted on a strainer placed in the well. A conventional drain valve comprises a valve stem slidably or fixedly mounted on the strainer, and a valve body fixed at the lower end of the valve stem, the valve body having a tapered peripheral surface capable of fitting in the drain port to close the drain port when the valve body is lowered, and also capable of moving upwardly to open the drain port.
In the above-mentioned conventional drain valve the closing and opening of the drain port is performed by the engagement and disengagement of the tapered peripheralsurface of the valve body with and from the edge of the drain port. Therefore, the edge of the drain port has to be properly finished or formed to conform with the contour of the tapered peripheral surface of the valve body to assure watertight closure when the valve body is lowered to fit in the drain port to close the drain port. However, if the taper or the inclination of the peripheral surface of the valve body is made small in order to produce greater wedge effect for a tighter fit, the thickness or height of the valve body has to be substantially great and the valve body has to be raised a substantially long distance to give sufficient opening between the valve body and the edge of the drain port for draining the water, which requires a larger space between the bottom of the strainer and the bottom of the well of the sink. Under actual circumstances the height or thickness of the valve body of conventional drain valves is quite limited and thus the taper or the inclination of the peripheral surface is relatively great. Because of the greater taper of the peripheral surface, the valve body comes in contact with the upper edge of the drain port in the form of a line instead of a surface, and thus there is less wedge effect and therefore less watertightness.
Moreover, conventional kitchen drain valves are not provided with proper holding means for holding the valve stem or valve body in an open position against the turbulence of the draining water when draining. Therefore, the valve body may be pulled down by the turbulence of the draining water to close the drain port during the draining process.
In a separate application by the same inventor, Ser. No. 173,610 filed on July 30, 1980 the inventor has proposed improved constructions of kitchen sink drain valve having a resilient member for frictionally holding the valve stem, and a disc type valve body to be used in conjunction with the valve stem provided with the resilient member. In this invention, the inventor proposes the use of an elastic disc type drain valve body independent from the valve stem constructions proposed in the aforesaid application.